Affiliation:
1. School of Materials Science and Engineering Harbin Institute of Technology Harbin 150001 China
2. Key Laboratory of Photochemical Conversion and Optoelectronic Materials and TIPC‐CityU Joint Laboratory of Functional Materials and Device Technical Institute of Physics and Chemistry Chinese Academy of Sciences Beijing 100190 China
3. School of Materials Science & Engineering Changzhou University Changzhou 213164 P. R. China
4. Research Institute for Physical Chemical Problems Belarusian State University Minsk 220006 Belarus
Abstract
AbstractMultiresonance thermally activated delayed fluorescence (MR‐TADF) emitters with high color purity in virtue of their inherent narrowband emission have received great interest in organic light‐emitting diodes (OLEDs). However, it remains a big challenge to develop the ultrapure blue MR‐TADF emitters with high efficiency. In this work, a novel “dual‐MR‐core” strategy is proposed by connecting two parent N‐B‐O‐skeletons with non‐conjugate 9‐position substituted fluorene linkages for high efficient deep‐blue MR‐TADF emitters, namely H‐FOBN and Me‐FOBN, which possess the highly twisted structure with suppressed aggregation. Finally, the vacuum‐deposited deep‐blue OLED exhibits excellent external quantum efficiency (EQE) of 25.1% with small full width at half maximum (FWHM) of 28 nm, as well as CIE of (0.14, 0.08). Furthermore, owing to enhanced solubility, the solution‐processed deep‐blue OLED based on Me‐FOBN shows EQE of 11.3%, with small FWHM of 32 nm and CIE of (0.14,0.09). These outstanding performances confirm that this “dual‐MR‐core” strategy provides a feasible approach to develop high efficient ultrapure blue MR‐TADF emitters.
Funder
National Natural Science Foundation of China